Enforce constraints at the start of nonlinear fitting

Bug: oss-fuzz:8130
Change-Id: I4dd5a2d85a9efa4b4bcaf83c520ef5d2168f997e
Reviewed-on: https://skia-review.googlesource.com/125732
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
4 files changed